Polishing fixture for simultaneous loading of a plurality of optical connectors and fiber stubs and a method of loading

ABSTRACT

A fixture for simultaneously clamping a number of optical fiber ferrules or fiber stubs for polishing. The fixture includes a plate assembly with an upper surface, a lower surface and a number of ferrule-receiving bores disposed across the upper surface and extending from the upper surface to the lower surface, each ferrule-receiving bore for receiving a ferrule. The fixture further includes a number of ferrule gripper arrangements, each associated with one of the ferrule-receiving bores, each of the ferrule gripper arrangements being selectively deployable between a released state for insertion of a ferrule into the ferrule-receiving bore and a gripping state in which the gripper arrangement clamps a ferrule within the ferrule-receiving bore. The fixture also includes a locking mechanism associated with at least a group of the number of ferrule gripper arrangements and configured to deploy the group of ferrule gripper arrangements substantially simultaneously from the released state to the gripping state so as to clamp substantially simultaneously a number of optical fiber ferrules located within a corresponding group of the ferrule-receiving bores.

FIELD OF THE INVENTION

The present invention relates to the field of polishing of connectorsand fiber stubs. More particularly the present invention relates to apolishing fixture and a method for simultaneous loading, reloading andpolishing a plurality of fiber stubs or optical connectors.

BACKGROUND OF THE INVENTION

With the growth of optical communication networks there is a growingneed for altering the network configuration, connecting to it new nodesand devices, disconnecting old devices and maintaining the network.These connections are easy and convenient to make with the help of anoptical connector, which is a demountable device for attaching anoptical fiber to another optical fiber, or to an active or passivedevice.

The losses of the optical signal power at each connection depend on thegeometry of the connector end-face, matching surfaces geometry, surfacequality and other parameters. In order to reduce optical signal powercoupling losses, the end-face of an optical connector, typicallycomprising an optical fiber inserted into a ferrule, is polished. Thepolished end-face surface may be flat, inclined or have a radius inaccordance with the type of connection desired. The term “ferrule” asused in the text of the disclosure means an optical connector thepolished end-face of which comprises a fiber inserted into a ferrule.The term “ferrule” as used herein includes optical connector having aferrule and fiber stubs.

Polishing of an optical connector on a piece-by-piece basis is notpractical due to the nature of the process as well as the mix of thequantities and the structure of the connectors to be polished. This isthe main reason why optical connectors are typically polished inbatches. In the context of the present invention, batch means aplurality of connectors polished or processed simultaneously. Forpolishing, a batch of optical connectors is loaded in a so-calledpolishing fixture. U.S. Pat. No. 5,961,374 to Minami et al. disclosessome such polishing fixtures. FIGS. 1A-1C illustrate some prior artpolishing fixtures that may have round, polygonal, or any other form. Inthese polishing fixtures the connectors, marked by numeral 80, areloaded or attached on one-by-one basis to the periphery of a polishingfixture 82. Each connector is secured in its mount with the help of ascrew 84. Upon completion of the polishing operation, the connectors areremoved from the polishing fixture one-by-one and a new batch ofconnectors mounted. Loading of a large number of the connectors on aone-by-one basis is a time consuming operation that to some extentreduces the throughput of a polishing system and requires additionallabor increasing the cost of the polished connectors.

U.S. Pat. Nos. 5,947,797, 6,183,343, and 6,190,239 all to Buzzettidisclose polishing fixture (FIG. 1D) where the connectors or similarlyconfigured industrial components to be polished are loaded across thefixture on a grid. This allows for simultaneous polishing of arelatively large number of optical connectors. Each of the connectors tobe polished is individually loaded and removed after polishing from thepolishing fixture. Each connector is secured in its mount with the helpof a screw or with the help of so-called tab-lock mechanism.

Loading of fiber stubs in a polishing fixture is even more complicated.The term “fiber stub” as used in the text of the disclosure means aferrule with inserted in it a relatively short section of optical fiber.Fiber stubs 86 typically have two ends, both of which must have polishedend-face surfaces. One of the ends is polished first. Following this,the partially polished stubs are removed from the polishing fixture,which as shown in FIG. 1E is a simple V-groove 88, and loaded once againfor polishing the second end face. A flat metal strip 90 or anotherV-groove with the help of screws 92 locks stubs 86 in V-groove 88. Theoperation is time consuming and error prone. Most accurate stubs 86handling does not results in fiber stubs having equal protrusion P andaccordingly of the end faces to be polished are not in the same plane.

Polishing fixtures are not versatile enough to adopt the variety ofexisting connectors. In practice each connector type, such as FC, SC, STand others require a dedicated polishing fixture. This forces thesupplier of polished optical fiber cables to stock a variety ofpolishing fixtures. Polishing fixtures are expensive and the stock costincreases the cost of polished optical fiber cables and connectors.

Certain cables have a multi fiber connector on one of its ends. Theother end of the same optical fiber cable may be split into a number ofsimplex or duplex connectors. Each of the connectors may be of adifferent type. Existing polishing fixtures do not support loading andpolishing of different types of connectors on the same fixture.Polishing of such cables requires their loading in a suitable fixturefor holding only one of the connector types with subsequent reloading ina polishing fixture that supports a different type of connector used ina particular cable. This naturally extends the cable production time andincreases the cost. Furthermore, different connectors of the same cableare polished at different conditions. This results in differences in thequality of the polished connectors, increased spoilage and additionalpolishing costs.

Polishing is usually conducted in the presence of water or speciallyformulated water-based or other fluid-based coolant or lubricant. Water(or other coolant) plays an important role in the polishing process.Water cools the part being polished, removes particles, contaminationand other debris that might otherwise destroy a polished connectorend-face made up of the fiber and ferrule surface. The supply rate ofwater is controlled to maintain proper concentration of polishingslurry, and the water provides lubrication between polished parts andpolishing substrate. Water (and sometimes other fluids) is usuallydelivered to the polishing member and to the actual polishing area,typically to the periphery of the polishing fixture by a fluid deliverysystem separate from the polishing fixture. International ApplicationPCT/IL03/00733 to the present assignee discloses a polishing fixturethat ensures proper water (coolant) delivery to each and every polishedconnector mounted on the polishing fixture. Despite the advantages ofthe fixture described therein, the connectors to be polished are stillloaded one-by-one. Water is conducted through special water conductingtubing distributed across the top of the fixture. The tubing occupiessome of the space required for more convenient connector loadingactivities.

There is no polishing fixture known to the inventors of the presentinvention enabling simultaneous loading (mounting) of a plurality(batch) of connectors to be polished. There is no polishing fixtureknown to the inventors of the present invention enabling simultaneouspolishing of different type of connectors loaded in the same polishingfixture.

Fibers protruding from connectors or fiber stubs loaded in a polishingfixture for polishing generally have to be cleaved or trimmed. Thecleaving procedure is supposed to make fibers protruding from theconnectors of equal length and ensure uniform pressure on each connectorpolished. However, since ferrules and connector housings have certaintolerances the ferrules protrusion with respect to the housing of theconnectors is not equal. Accordingly, the pressure developed by thepolishing process is different for each connector. There are nopolishing fixture loading methods known to the inventors of the presentinvention that ensure equal protrusion of connectors or their ferrulesloaded in a polishing fixture.

It would be desirable to have a polishing fixture enabling simultaneousloading of a plurality (batch) of connectors or fiber stubs to bepolished. It would be also desirable to have a polishing fixture, whichwould ensure equal protrusion of the loaded connectors or fiber stubs tobe polished.

The industry is in need of a polishing fixture that would allow loadingof a plurality of different connector types in the same polishingfixture and their subsequent polishing in the same polishing fixture.

Polishing fixtures having water-conducting tubing within the body of thefixture that would not occupy the space across the top of the fixtureand would thereby facilitate more convenient connector loadingactivities would better serve the polishing industry needs.

The industry needs a polishing fixture and a polishing fixture loadingmethod that would ensure equal protrusion of connectors or theirferrules loaded in a polishing fixture and accordingly apply equalpressure developed by the polishing process to each connector.

SUMMARY OF THE INVENTION

The present invention is a polishing fixture enabling simultaneousloading and simultaneous polishing of a plurality (batch) of connectorsor fiber stubs to be polished.

According to the teachings of the present invention there is provided, afixture for simultaneously clamping a plurality of optical fiberferrules or fiber stubs for polishing. The fixture optionally andpreferably includes a plate assembly having an upper surface, a lowersurface and a plurality of ferrule-receiving bores disposed across theupper surface and extending from the upper surface to the lower surface,each ferrule-receiving bore for receiving a ferrule. The fixture furtherincludes a plurality of ferrule gripper arrangements. Each arrangementis associated with one of the ferrule-receiving bores, each of theferrule gripper arrangements being selectively deployable between areleased state for insertion of a ferrule into the ferrule-receivingbore and a gripping state. In the gripping state the gripper arrangementclamps a ferrule within the ferrule-receiving bore; and a lockingmechanism associated with at least a group of the plurality of ferrulegripper arrangements. The locking mechanism is configured to deploy thegroup of ferrule gripper arrangements substantially simultaneously fromthe released state to the gripping state so as to clamp substantiallysimultaneously a plurality of optical fiber ferrules located within acorresponding group of the ferrule-receiving bores.

According to a further teaching of the present invention, the plateassembly includes an upper plate providing the upper surface and a lowerplate providing the lower surface, and the plurality of ferrule gripperarrangements that are substantially enclosed between the upper and lowerplates.

According to still a further teaching of the present invention, thelocking mechanism includes a gripper carrier and an actuator mechanismfor displacing the gripper carrier, and wherein the group of ferrulegripper arrangements is implemented as resilient elements mechanicallyinterconnected to be displaced together with the gripper carrier.

According to an additional feature of the present invention, each of theferrule-receiving bores has an internal diameter of no more than about 3millimeters.

In agreement with a further teaching of the present invention, thefixture preferably includes a loading plate that assists in loading of aplurality of connectors or fiber stubs in the fixture. The loading platehas a loading calibration surface having a plurality of alignmentopenings. Each opening is configured to define a degree of projection(protrusion) of a ferrule or a fiber stub from a corresponding one ofthe ferrule-receiving bores. The loading plate and the plate assemblyfeaturing inter-engaging alignment features configured to align theloading plate with the lower surface such that one of the alignmentopenings is aligned with each of the ferrule-receiving bores.

According to an additional teaching of the present invention, thefixture preferably further includes a fiber-stub insertion toolincluding at least one spring-loaded pin configured for pressing a fiberstub to a fully inserted position within one of the ferrule-receivingbores.

In agreement with an additional teaching of the present invention, thefixture preferably further includes a fiber-stub inversion assembly thatassists in the fiber-stubs loading for polishing of one of the end-facesand automatic inversion of the stubs in the same fixture for polishingthe second end-face.

According to a further teaching of the present invention, the fiber-stubinversion assembly preferably includes a storage plate having aplurality of fiber-stub-receiving openings disposed on a surface of thestorage plate in a pattern similar to a pattern of the ferrule-receivingbores and a support mechanism configured to support the storage plate.The support mechanism optionally and preferably includes an inversionmechanism for selectively allowing inversion of the storage plate.

According to a further teaching of the present invention, the fiber-stubinversion assembly and the plate assembly of the fixture preferablyinclude inter-engaging alignment features configured to align thestorage plate with each of the lower surface and the upper surface suchthat one of the fiber-stub-receiving openings is aligned with each ofthe ferrule-receiving bores.

According to an additional teaching of the present invention, thefixture may further include a mounting arm projecting from the uppersurface of the plate assembly, and the storage plate is formed with anopening configured to accommodate the mounting arm when the storageplate is aligned with the upper surface.

According to a further teaching of the present invention, the fixturepreferably includes a plurality of fiber-stub-receiving openings formedin a first surface of the storage plate. The storage plate furtherincludes a second surface being a loading calibration surface formedwith a plurality of alignment openings each configured to define adegree of projection of a ferrule from a corresponding one of theferrule-receiving bores. Both surfaces of the storage plate and theplate assembly preferably feature inter-engaging alignment featuresconfigured to align the storage plate with the surfaces of plateassembly such that one of the alignment openings is aligned with each ofthe ferrule-receiving bores.

The present invention further provides a method for simultaneouslyclamping a plurality of optical fiber ferrules or fiber stubs forpolishing. The method optionally and preferably includes steps of:providing a fixture including a plate assembly having a plurality offerrule-receiving bores, a plurality of ferrule gripper arrangements,each associated with one of the ferrule-receiving bores, and a lockingmechanism associated with at least a group of the plurality of ferrulegripper arrangements. Deploying a plurality of optical fiber ferruleswithin the ferrule-receiving bores and operating the locking mechanismto cause at least the group of ferrule gripper arrangements tosubstantially simultaneously clamp a group of the ferrules within acorresponding group of the ferrule-receiving bores.

According to the method of the present invention, the step of providingthe plate assembly includes an assembly having an upper plate providingan upper surface and a lower plate providing a lower surface, and theplurality of ferrule gripper arrangements that are substantiallyenclosed between the upper and lower plates. The locking mechanismincludes a gripper carrier and the group of ferrule gripper arrangementsare implemented as resilient elements mechanically interconnected withthe gripper carrier, and the step of operating the locking mechanism isbeing performed by operating an actuator mechanism to displace thegripper carrier and hence the resilient elements.

According to a further feature of the method of the present invention,each of the ferrule-receiving bores has an internal diameter of no morethan about 3 millimeters.

According to an additional feature of the method of the presentinvention, the step of bringing the loading plate calibration surfaceinto juxtaposition with the plate assembly so as to define a desireddegree of projection of the ferrules from the ferrule-receiving boresprecedes the step of deploying the ferrules within the ferrule receivingbores. The step of the calibration surface of the loading plate and theplate assembly separation is subsequent to the step of operating of thelocking mechanism.

According to a further feature of the method of the present invention,the loading plate calibration surface features a plurality of alignmentopenings for cooperation with end portions of the ferrules, the bringinginto juxtaposition being performed to align the alignment openings withcorresponding of the ferrule-receiving bores.

In agreement with the method of the present invention, preferably a stepof employing at least one spring-loaded pin for pressing a fiber stub toa fully inserted position within one of the ferrule-receiving bores isused.

The method of the present invention preferably further includes the stepof polishing a first end of a plurality of fiber-stubs while the fiberstubs are clamped in the fixture in a first orientation. The step ofpolishing is followed by the step of off-loading the plurality offiber-stubs substantially simultaneously into fiber-stub-receivingopenings of a storage plate and the step of reloading the plurality offiber-stubs substantially simultaneously into the ferrule-receivingbores of the plate assembly. The step of reloading places the fiberstubs in a second orientation inverted relative to the first orientationand the step of operating the locking mechanism is performed so as tosubstantially simultaneously clamp the fiber-stubs within theferrule-receiving bores.

The present invention further provides a method of polishing of bothends of a plurality of optical fiber stubs. The method preferablyincludes the steps of providing a fixture including a plate assemblyhaving an upper surface, a lower surface and a plurality offerrule-receiving bores extending from the upper surface to the lowersurface, each ferrule-receiving bore for receiving a fiber stub, and aplurality of ferrule gripper arrangements, each associated with one ofthe ferrule-receiving bores. Providing a fiber-stub inversion assemblyincluding a storage plate, a plurality of fiber-stub-receiving openingsdisposed on a surface of the storage plate in a pattern similar to apattern of the ferrule-receiving bores, and a support mechanismconfigured to support the storage plate, the support mechanism includingan inversion mechanism for selectively allowing inversion of the storageplate. Deploying and clamping a plurality of optical fiber stubs withinthe ferrule-receiving bores with a first end of each of the fiber stubsprojecting from the lower surface. Polishing the first ends of the fiberstubs and bringing the plate assembly into juxtaposition with thestorage plate such that the ferrule-receiving bores are aligned with thefiber-stub-receiving openings. Releasing and off-loading the fiber stubsfrom the ferrule-receiving bores into the fiber-stub-receiving openings.Inverting the plate assembly and bringing the plate assembly intoinverted juxtaposition with the storage plate such that theferrule-receiving bores are aligned with the fiber-stub-receivingopenings. Re-loading the fiber stubs from the fiber-stub-receivingopenings into the ferrule-receiving bores and clamping the fiber stubswithin the ferrule-receiving bores with a second end of each of thefiber stubs projecting from the lower surface and polishing the secondends of the fiber stubs.

In accordance with the method of polishing of the present invention, thestep of re-loading includes inverting the plate assembly together withthe storage plate. And the steps of the deploying and the re-loadingboth include bringing the plate assembly into juxtaposition with theloading calibration surface, the calibration surface having a pluralityof alignment openings each configured to define a degree of projectionof the fiber stub from a corresponding one of the ferrule-receivingbores. The loading calibration surface is implemented as one of thesurfaces of the storage plate.

According to the method of polishing of the present invention, the stepsof deploying and clamping and the re-loading and clamping includeoperating a locking mechanism to simultaneously operate a plurality ofthe ferrule gripper arrangements, and at least the step of deployingincludes employing a fiber-stubs insertion tool. The insertion toolincludes at least one spring-loaded pin for pressing a fiber stub to afully inserted position within one of the ferrule-receiving bores.

The present invention provides a polishing fixture for simultaneouslyclamping (loading) and polishing of a plurality of connector end faceswherein the connectors are held in the polishing fixture by applyingpressure to their ferrules. Since ferrules of different types ofconnectors have similar size loading of different types of connectors onthe same polishing fixture is enabled.

Another feature of the present invention is a method of polishing of endfaces of a plurality of connectors wherein the connectors are held inthe polishing fixture by applying pressure to their ferrules.

The present invention significantly reduces the time required forloading a polishing fixture with a plurality of connectors or ferrulesto be polished and accordingly reduces the polishing costs.

Connectors or fiber stubs loaded in a polishing fixture for polishinghave a uniform projection (protrusion) length that does not depend onthe ferrule within connector housing position. The polishing force isequally distributed between the connectors or fiber stubs furtherimproving polishing quality and yield.

Polishing is a process where abrasive materials and polishing debris areusually accumulated in the polishing fixture. The present inventionsupports easy polishing fixture assembly and dismantling and enableseasy polishing fixture cleaning.

The present invention also supports reloading of the polishing fixturewith a plurality of connectors or ferrules to be polished and furtherreduces the polishing costs.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention is herein described, by way of non-limiting examples only,with reference to the accompanying drawings, wherein:

FIGS. 1A-1E are schematic illustrations of prior art polishing fixtures;

FIG. 2 is a three dimensional illustration of the assembly of anexemplary embodiment of the fixture for simultaneously clamping aplurality of optical fiber ferrules or fiber stubs for polishing of thepresent invention;

FIG. 3 is a bottom view of a three dimensional illustration of theassembly of an exemplary embodiment of the fixture for simultaneouslyclamping a plurality of optical fiber ferrules or fiber stubs forpolishing of the present invention;

FIG. 4 is a partial cross sectional bottom view of the assembly of anexemplary embodiment of the fixture for simultaneously clamping aplurality of optical fiber ferrules or fiber stubs for polishing of thepresent invention;

FIG. 5 is an illustration of an exemplary embodiment of the ferrulegripper arrangement, which is part of the locking mechanism of thepresent invention;

FIG. 6 is a top view illustration of an exemplary embodiment of theloading plate of the present invention;

FIG. 7 is a cross-section of an exemplary embodiment of polishingfixture of FIGS. 2-4 coupled with loading plate, which is part of thepresent invention;

FIG. 8 is a schematic three-dimensional illustration of the assembly ofan exemplary embodiment of the fiber-stub insertion tool, which is partof the present invention;

FIG. 9 is a schematic cross-section of an exemplary embodiment ofpolishing fixture of FIGS. 2-4 coupled with loading plate and loaded bydifferent types of ferrules and connectors to be polished, which is partof the present invention;

FIG. 10 is a schematic magnified cross section of FIG. 9, which is partof the present invention;

FIGS. 11A, 11B and 11C are schematic three-dimensional illustrations ofan exemplary embodiment of the fiber-stub inversion assembly of thepresent invention;

FIG. 12 is a schematic flow chart illustration of the method of clamping(loading) a plurality of optical fiber ferrules or fiber-stubs forpolishing according to the present invention;

FIG. 13 is a schematic flow chart illustration of the method ofpolishing of both ends of optical fiber stubs according to the presentinvention;

FIG. 14 schematically illustrates a step of the method of simultaneousclamping a plurality of optical fiber ferrules or fiber stubs in apolishing fixture according to the present invention;

FIG. 15 schematically illustrates a step of the method of polishing bothends of a plurality of optical fiber stubs according to the presentinvention;

FIGS. 16 is a magnified schematic cross section of FIG. 15, which ispart of the present invention;

FIGS. 17 schematically illustrates another step of the method ofpolishing both ends of a plurality of optical fiber stubs according tothe present invention;

FIGS. 18 is a magnified schematic cross section of FIG. 17, which ispart of the present invention;

FIG. 19 schematically illustrates a further step of the method ofpolishing both ends of a plurality of optical fiber stubs according tothe present invention;

FIGS. 20 is a magnified schematic cross section of FIG. 19, which ispart of the present invention;

FIGS. 21 schematically illustrates an additional step of the method ofpolishing both ends of a plurality of optical fiber stubs according tothe present invention;

FIG. 22 is a schematic top view illustration of a polishing systememploying the polishing fixture of the present invention.

DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS

The principles and execution of a method according to the presentinvention, and the operation and properties of the fixture, loadingplate, fiber stub insertion tool and fiber stub inversion assemblydescribed thereby may be understood with reference to the drawings,wherein like reference numerals denote like elements through the severalviews and the accompanying description of non-limiting, exemplaryembodiments.

Reference is now made to FIGS. 2, 3 and 4 that illustrate an exemplaryembodiment of the fixture for simultaneously clamping a plurality ofoptical fiber ferrules or fiber stubs for polishing of the presentinvention. Polishing fixture 100 optionally and preferably includes aplate assembly 106 having an upper surface 130, a lower surface 132 anda plurality of ferrule-receiving bores 104 disposed across the uppersurface and extending from upper surface 130 to lower surface 132, eachferrule-receiving bore 104 for receiving a ferrule 138 (FIG. 4). Fixture100 further includes a plurality of ferrule gripper arrangements 126(FIG. 4). Each arrangement 126 is associated with one of theferrule-receiving bores 104, each of ferrule gripper arrangements 126being selectively deployable between a released state for insertion of aferrule into ferrule-receiving bore 104 and a gripping state. In thegripping state gripper arrangement 126 clamps ferrule 138 withinferrule-receiving bore 104; and a locking mechanism associated with atleast a group of the plurality of ferrule gripper arrangements 142 (FIG.5). Locking mechanism is configured to deploy the group of ferrulegripper arrangements 142 substantially simultaneously from the releasedstate to the gripping state so as to clamp substantially simultaneouslya plurality of optical fiber ferrules 138, although only one ferrule isshown, located within a corresponding group of the ferrule-receivingbores 104.

Plate assembly 106 includes an upper plate 102 providing upper surface130 and a lower plate 108 providing lower surface 132, and plurality offerrule gripper arrangements 142 are substantially enclosed betweenupper 102 and lower 108 plates.

Locking mechanism includes a gripper carrier 126 and an actuatormechanism 128 for displacing gripper carrier 126. Locking mechanism maybe any mechanism that ensures rapid deployment of the group of ferrulegripper arrangements 142 from the released state to the gripping stateand it may be a quarter turn screw, or a cam, or magnetic plates, orother similar devices. Each group of ferrule gripper arrangements 126 isimplemented as resilient elements 124 and 140 mechanicallyinterconnected (FIGS. 4 and 5) to be displaced together with grippercarrier 126. Each of ferrule-receiving bores 104 has an internaldiameter of no more than about 3 millimeters.

Fixture 100 may optionally include coolant conducting channels 114 (FIG.4) disposed along and across of at least one of plates 102 or 108. Inthe particular case coolant conducting channels 114 are made withinplate 102. Coolant conducting channels 114 (FIG. 4) have coolantdelivery 116 and supply 118 outlets. Coolant delivery outlets 116 are influid communication with coolant delivery outlets 120 of second plate108. Coolant conducting channels 114 receive coolant supply from acentral coolant supply source 122. Coolant flows from central coolantsupply source 122 to coolant supply outlets 118 located at the centralarea of fixture 100 to the periphery of fixture 100 via coolantconducting channels 114.

According to the teaching of the present invention, fixture 100preferably includes a loading plate 150 that assists in loading of aplurality of connectors or fiber stubs in fixture 100. Loading plate 150has a loading calibration surface 154 having a plurality of alignmentopenings 156 (FIG. 7). Each opening 156 is configured to define a degreeof projection (protrusion) P of a ferrule from a corresponding one offerrule-receiving bores 104. Loading plate 150 and the plate assembly100 are featuring inter-engaging alignment features 162 and 136configured to align loading plate 150 with lower surface 132 such thatone of alignment openings 156 is aligned with each of ferrule-receivingbores 104.

Shown in FIG. 7 for illustration purposes only are a ferrule 138 and aconnector 160 having a ferrule 158, deployed in their respective ferrulereceiving bores 104 and resting on the edges of alignment openings 156of loading plate 150. Alignment openings 156 accept fibers 168protruding out of ferrules and ensure that ferrules resting on the edgesof openings 156 will have equal protrusion regardless the length of thefiber protruding out of the ferrules.

Loading plate 150 may be of a stand-alone construction or alternativelyit may have leg type inserts 164 to be positioned on a worktable wherethe loading of polishing fixture 100 takes place.

Fixture 100 preferably further includes a fiber-stub insertion tool 166shown in FIG. 8. Tool 166 includes a plurality of spring-loaded pins 178configured for pressing a fiber stub 138 (FIG. 9) to a fully insertedposition within respective ferrule-receiving bores 104. Tool 166 mayfurther include a solid plate 170 having and a handle 176 attached toupper surface 186 of plate 170. Handle 176 facilitates tool 166handling. Pins 178 have freedom of axial movement in the directionindicated by arrow 180. Spring 182 (FIGS. 9 and 10) acts in such a waythat a non-obstructed pin would have its end 184 become flash with uppersurface 186 of solid plate 170. When deployed in ferrule-receiving bore104 fiber-stubs (ferrules) 138 cannot be observed. The flash position ofpin end 184 indicates that fiber stub 138 is in fully inserted position.The particular fiber-stub insertion tool 166 has a two dimensional arrayof pins 178. Depending on the form of gripper carriers 126 there may bea linear array of pins 178 and in some cases only one pin 178 may beused.

Fixture 100 preferably further includes a fiber-stub inversion assembly200 shown in FIGS. 11A-11C. Fiber-stub inversion assembly 200 assists inthe fiber-stubs loading for polishing of one of the end-faces andautomatic inversion of the stubs in the same fixture for polishing thesecond end-face. According to the teaching of the present invention,assembly 200 preferably includes a storage plate 202 having a pluralityof fiber-stub-receiving openings 208 disposed on a surface 220 andextending from surface 220 to surface 226, of storage plate 202 in apattern similar to a pattern of the ferrule-receiving bores 104 and asupport mechanism. Surface 220 is implemented similar to loadingcalibration surface 150, and fiber-stub-receiving openings 208 disposedon surface 220 feature alignment openings similar to alignment openings156 (FIG. 7). Each opening 156 is configured to define a degree ofprojection (protrusion) P of a ferrule from a corresponding one offerrule-receiving bores 104. Support mechanism may include stand 240 andplate 228 configured to support storage plate 202. The support mechanismoptionally and preferably includes an inversion mechanism 230 forselectively allowing inversion of storage plate 202.

Storage plate 202 of fiber-stub inversion assembly 200 and plateassembly 106 of fixture 100 preferable include inter-engaging alignmentfeatures 212, 214 and 136. Inter-engaging alignment features 212, 214and 136 are configured to align surfaces 220 and 226 of storage plate202 with each of lower surface 132 and upper surface 130 such that oneof fiber-stub-receiving openings 208 or one of alignment openings 156 isaligned with each of ferrule-receiving bores 104.

Inversion assembly 200 optionally may have a number of screws 218 orother fast locking mechanism for locking in a fixed position juxtaposedwith it fixture 100. Such locking mechanism enables more convenientoperator work.

Fixture 100 may preferably further include a mounting arm 134 (FIG. 2)projecting from upper surface 130 of plate assembly 106, and storageplate 202 is formed with an opening configured to accommodate mountingarm 134 when storage plate 202 is aligned with upper surface 130.

The present invention further provides a method for simultaneouslyclamping a plurality of optical fiber ferrules or fiber stubs forpolishing. The method optionally and preferably includes steps of:providing a fixture 100 including a plate assembly 106 having aplurality of ferrule-receiving bores 104, a plurality of ferrule gripperarrangements 126, each associated with one of the ferrule-receivingbores 104, and a locking mechanism associated with at least a group ofthe plurality of ferrule gripper arrangements 142. Providing a loadingplate 150 having a loading calibration surface 154 and a fiber-stubinsertion tool 166 (Step 320).

Plate assembly 106 (FIGS. 2-4) includes an assembly having an upperplate 102 providing an upper surface 130 and a lower plate 108 providinga lower surface 132, and the plurality of ferrule gripper arrangements126 that are substantially enclosed between upper 102 and lower 108plates. Locking mechanism includes a gripper carrier 126 and a group offerrule gripper arrangements 124 and 140 implemented as resilientelements mechanically interconnected with the gripper carrier 126.Actuator mechanism operates locking mechanism to displace grippercarrier 126 and hence resilient elements 124 and 140. Loadingcalibration surface 154 of loading plate 150 features a plurality ofalignment openings 156 for cooperating with end portions 144 and 146 offerrules 138.

Bringing loading calibration surface 154 of loading plate 150 (Step 322)into juxtaposition with plate assembly 106 to define a desired degree ofprojection (protrusion) of ferrules 138 from ferrule-receiving bores104. Operating the locking mechanism for deploying a group of ferrulegripper arrangements 126 to the released state (Step 324) and deployinga plurality of optical fiber ferrules 138 within ferrule-receiving bores104 (Step 326). Employing spring-loaded pins 178 of fiber-stub insertiontool 166 (Step 328) for pressing fiber stubs 138 to a fully insertedposition within ferrule-receiving bores 104. Operating the lockingmechanism (Step 330) to cause at least a group of ferrule gripperarrangements 126 to substantially simultaneously clamp a group offerrules 138 within a corresponding group of ferrule-receiving bores104.

The method for simultaneously clamping a plurality of optical fiberferrules or fiber stubs for polishing preferably further includes stepof polishing (Step 332) a first end 144 (FIGS. 15, 17, 19 and 21) of aplurality of fiber-stubs (ferrules) 138 while fiber stubs 138 areclamped in fixture 100 in a first orientation. Step of polishing isfollowed by step of off-loading (Step 334) of the plurality offiber-stubs substantially simultaneously into fiber-stub-receivingopenings 208 of storage plate 202 (FIG. 14) and step of reloading (Step336) the plurality of fiber-stubs 138 substantially simultaneously intoferrule-receiving bores 104 of plate assembly 106. Reloading step 336places fiber stubs in a second orientation, inverted relative to thefirst orientation with ferrule second end 146 facing downward (FIG. 19).The locking mechanism is operated at step 338 to substantiallysimultaneously clamp the fiber-stubs 138 within ferrule-receiving bores104.

The present invention further provides a method of polishing of bothends of a plurality of optical fiber stubs. The method illustrated inFIG. 13 preferably includes steps of: providing a fixture 100 includinga plate assembly 106 having an upper surface 130, a lower surface 132and a plurality of ferrule-receiving bores 104 extending from uppersurface 130 to lower surface 132. Each ferrule-receiving bore 104receives a fiber stub 138, and a plurality of ferrule gripperarrangements 126, each associated with one of ferrule-receiving bores104. Providing a fiber-stub inversion assembly 200 including a storageplate 202, a plurality of fiber-stub-receiving openings 208 disposed ona surface 220 of storage plate 202 in a pattern similar to a pattern offerrule-receiving bores 104, and a support mechanism 228 and 240configured to support storage plate 202. Support mechanism includes aninversion mechanism 230 for selectively allowing inversion of storageplate 202 (Step 350). Deploying (Step 352) and clamping (Step 354) aplurality of optical fiber stubs 138 within ferrule-receiving bores 104with a first end 144 of each of fiber stubs 138 projecting from lowersurface 132. Polishing (Step 356) first ends 144 of fiber stubs 138 andbringing plate assembly 106 (Step 358) into juxtaposition with storageplate 202 such the ferrule-receiving bores 104 are aligned (FIG. 15)with fiber-stub-receiving openings 208. Releasing and off-loading fiberstubs 138 (Step 360) from ferrule-receiving bores 104 intofiber-stub-receiving openings 208. Inverting plate assembly 106 andbringing plate assembly 106 into inverted juxtaposition (Step 362) withstorage plate 202 (FIGS. 16 and 17) such that ferrule-receiving bores104 are aligned with fiber-stub-receiving openings 208. Re-loading (Step364) the plurality of fiber stubs 138 from fiber-stub-receiving openings208 into ferrule-receiving bores 104 (FIGS. 18 and 19) and clamping(Step 366) fiber stubs 138 within ferrule-receiving bores 104 with asecond end 146 of each of fiber stubs 138 projecting from lower surface132 and polishing (Step 368) second ends 146 of the fiber stubs 138.

According to the method of polishing of the present invention, step ofre-loading (Step 364) includes inverting plate assembly 106 togetherwith storage plate 202 having a plurality of fiber-stub-receivingopenings 208 disposed on a surface 220 and extending from surface 220 tosurface 226. Fiber-stub-receiving openings 208 disposed on a surface 220feature alignment openings similar to alignment openings 156 (FIG. 7).The steps of the deploying (Step 352) and the re-loading (Step 364) bothinclude bringing plate assembly 106 into juxtaposition with storageplate 202, having a plurality of alignment openings 208 each configuredto define a degree of projection of fiber stub 138 from a correspondingone of ferrule-receiving bores 104.

The steps of deploying (Step 352) and clamping (Step 366) and the stepsof re-loading (Step 364) and clamping (Step 366) include operating alocking mechanism to simultaneously operate a plurality of ferrulegripper arrangements 142, and at least step of deploying (Step 352)includes employing an insertion tool 166. Insertion tool 166 includes atleast one spring-loaded pin 178 for pressing a fiber stub 138 to a fullyinserted position within one of ferrule-receiving bores 104.

FIG. 22 is a schematic top view illustration of polishing systememploying polishing fixture 100 of the present invention. Polishingsystem 400 per se in not a part of the invention and it is described indetail in an International Application PCT/IL03/00733 to the presentassignee. Polishing system 400 may include a main frame 402 on which aflat and rigid plate 404 may be mounted. Optionally attached to the topsurface of plate 154 may be some sub-systems included in polishingstation 400. FIG. 23 shows a polishing sub-system 408 containing anumber of polishing units 410. A cleaning unit 412 for cleaning polishedoptical connectors of polishing process contaminations may also bepositioned on the top part of plate 404. For the simplicity ofexplanation, plate 404 is shown cut away in a number of places, as willbe clear from the following description. A rinsing and drying unit 414and wiping unit 416 may be located on the top part of plate 404. Acut-away region of plate 404 renders visible polished connectorsinspection unit 420. Inspection unit 420 may optionally be positioned ina recess of the top plate 404 and may be attached to the bottom surfaceof plate 404.

Polishing fixture 100 with a plurality of optical connectors (not shown)is attached by means of projection 134 (See FIG. 2) to a rigid mount424. Rigid mount 424 optionally and preferably has freedom of movementin X, Y and Z directions. Digitally controlled linear actuators 426,428, and 430 provide respectively movement in X, Y, and Z directions.Digital control facilitates independent movement in each of the X, Y,and Z movement directions. Linear actuators 426, 428, and 430 can moveand position polishing fixture 100 to virtually any point located on thetop part of plate 404 of polishing system 400. Linear actuators 426,428, and 430 optionally and preferably provide both operational,movements required for the polishing of optical connectors, andauxiliary movements required for positioning polishing fixture 100. Whenmoving polishing fixture 100 from one sub-system to other sub-system,linear actuators 426, 428, and 430 function as a built-in roboticsystem.

The polishing process begins with coupling of polishing fixture 100 witha plurality of ferrules 138 (optical connectors of fiber stubs) by meansof projection 134 (See FIG. 2) to a rigid mount 424. Digitallycontrolled linear actuators 426, 428, and 430 move fixture 100 from thecleaving unit to polishing sub-system 406 where plurality of ferules 138is polished, to cleaning unit 412 where plurality of ferules 138 iscleaned and so on till all processes including inspection areaccomplished.

The present invention provides a polishing fixture for simultaneouslyclamping (loading) and polishing of a plurality (batch) of connector endfaces wherein the connectors are hold in the polishing fixture byapplying pressure to their ferrules.

The present invention additionally provides a method of simultaneousclamping (loading) and off-loading of a polishing fixture by a pluralityof connectors and fiber stubs end faces of which have to be polished.

Another feature of the present invention is a method of polishing of endfaces of a plurality (batch) of connectors wherein the connectors arehold in the polishing fixture by applying pressure to their ferrules.

The present invention significantly reduces the time required forloading a polishing fixture with a plurality of connectors or ferrulesto be polished and accordingly reduces the polishing costs.

Connectors or fiber-stubs loaded in a polishing fixture for polishinghave a uniform protrusion length. The polishing force is equallydistributed between the connectors or fiber stubs further improvingpolishing quality and yield.

The present invention also supports fast re-loading of the polishingfixture with a plurality of connectors or fiber stubs to be polished andfurther reduces the polishing costs. In course of the reloading ferrulesare automatically inverted and their position reducing the possibilityof contamination or scratches of already polished end faces.

While the exemplary embodiments of the present invention have beenillustrated and described, it will be appreciated that various changescan be made therein without affecting the spirit and scope of theinvention.

1. A fixture for simultaneously clamping a plurality of optical fiber ferrules or fiber stubs for polishing, the fixture comprising: (a) a plate assembly having an upper surface, a lower surface and a plurality of ferrule-receiving bores disposed across said upper surface and extending from said upper surface to said lower surface, each ferrule-receiving bore for receiving a ferrule; (b) a plurality of ferrule gripper arrangements, each associated with one of said ferrule-receiving bores, each of said ferrule gripper arrangements being selectively deployable between a released state for insertion of a ferrule into said ferrule-receiving bore and a gripping state in which said gripper arrangement clamps a ferrule within the ferrule-receiving bore; and (c) a locking mechanism associated with at least a group of said plurality of ferrule gripper arrangements and configured to deploy said group of ferrule gripper arrangements substantially simultaneously from said released state to said gripping state so as to clamp substantially simultaneously a plurality of optical fiber ferrules located within a corresponding group of said ferrule-receiving bores.
 2. The fixture of claim 1, wherein said plate assembly includes an upper plate providing said upper surface and a lower plate providing said lower surface, and wherein said plurality of ferrule gripper arrangements are substantially enclosed between said upper and lower plates.
 3. The fixture of claim 1, wherein said locking mechanism includes a gripper carrier and an actuator mechanism for displacing said gripper carrier, and wherein said group of ferrule gripper arrangements are implemented as resilient elements mechanically interconnected so as to be displaced together with said gripper carrier.
 4. The fixture of claim 1, wherein each of said ferrule-receiving bores has an internal diameter of no more than about 3 millimeters.
 5. The fixture of claim 1, further comprising a loading plate with a loading calibration surface having a plurality of alignment openings each configured to define a degree of projection of a ferrule from a corresponding one of said ferrule-receiving bores, said loading plate and said plate assembly featuring inter-engaging alignment features configured to align said loading plate with said lower surface such that one of said alignment openings is aligned with each of said ferrule-receiving bores.
 6. The fixture of claim 1, further comprising a fiber-stub insertion tool including at least one spring-loaded pin configured for pressing a fiber stub to a fully inserted position within one of said ferrule-receiving bores.
 7. The fixture of claim 1, further comprising a fiber-stub inversion assembly including: (a) a storage plate; (b) a plurality of fiber-stub-receiving openings disposed on a surface of said storage plate in a pattern similar to a pattern of said ferrule-receiving bores; and (c) a support mechanism configured to support said storage plate, said support mechanism including an inversion mechanism for selectively allowing inversion of said storage plate.
 8. The fixture of claim 7, wherein said fiber-stub inversion assembly and said plate assembly feature inter-engaging alignment features configured to align said storage plate with each of said lower surface and said upper surface such that one of said fiber-stub-receiving openings is aligned with each of said ferrule-receiving bores.
 9. The fixture of claim 8, wherein the fixture further comprises a mounting arm projecting from said upper surface of said plate assembly, and wherein said storage plate is formed with an opening configured to accommodate said mounting arm when said storage plate is aligned with said upper surface.
 10. The fixture of claim 7, wherein said plurality of fiber-stub-receiving openings are formed in a first surface of said storage plate, and wherein said storage plate further includes a second surface formed with a plurality of alignment openings each configured to define a degree of projection of a ferrule from a corresponding one of said ferrule-receiving bores, said second surface and said plate assembly featuring inter-engaging alignment features configured to align said second surface with said lower surface such that one of said alignment openings is aligned with each of said ferrule-receiving bores.
 11. A method for simultaneously clamping a plurality of optical fiber ferrules or fiber stubs for polishing, the method comprising: (a) providing a fixture including: (i) a plate assembly having a plurality of ferrule-receiving bores, (ii) a plurality of ferrule gripper arrangements) each associated with one of said ferrule-receiving bores, and (iii) a locking mechanism associated with at least a group of said plurality of ferrule gripper arrangements; (b) deploying a plurality of optical fiber ferrules within said ferrule-receiving bores; and (c) operating the locking mechanism so as to cause at least said group of ferrule gripper arrangements to substantially simultaneously clamp a group of said ferrules within a corresponding group of said ferrule-receiving bores.
 12. The method of claim 11, wherein said plate assembly includes an upper plate providing an upper surface and a lower plate providing a lower surface, and wherein said plurality of ferrule gripper arrangements are substantially enclosed between said upper and lower plates.
 13. The method of claim 11, wherein said locking mechanism includes a gripper carrier, and wherein said group of ferrule gripper arrangements are implemented as resilient elements mechanically interconnected with said gripper carrier, said operating being performed by operating an actuator mechanism so as to displace said gripper carrier and hence said resilient elements.
 14. The method of claim 11, wherein each of said ferrule-receiving bores has an internal diameter of no more than about 3 millimeters.
 15. The method of claim 11, further comprising, prior to said deploying, bringing a loading calibration surface into juxtaposition with said plate assembly so as to define a desired degree of projection of said ferrules from said ferrule-receiving bores, said loading calibration surface and said plate assembly being separated subsequent to said operating of the locking mechanism.
 16. The method of claim 15, wherein said loading calibration surface features a plurality of alignment openings for cooperating with end portions of said ferrules, said bringing into juxtaposition being performed so as to align the alignment openings with corresponding of said ferrule-receiving bores.
 17. The method of claim 11, further comprising employing at least one spring-loaded pin for pressing a fiber stub to a fully inserted position within one of said ferrule-receiving bores.
 18. The method of claim 11, further comprising: (a) polishing a first end of a plurality of fiber-stubs while the fiber stubs are clamped in the fixture in a first orientation; (b) offloading said plurality of fiber-stubs substantially simultaneously into fiber-stub-receiving openings of a storage plate; (c) reloading said plurality of fiber-stubs substantially simultaneously into the ferrule-receiving bores of the plate assembly in a second orientation inverted relative to said first orientation and operating the locking mechanism so as to substantially simultaneously clamp said fiber-stubs within said ferrule-receiving bores.
 19. A method for polishing both ends of a plurality of optical fiber stubs, the method comprising: a providing a fixture including: (i) a plate assembly having an upper surface, a lower surface and a plurality of ferrule-receiving bores extending from said upper surface to said lower surface, each ferrule-receiving bore for receiving a fiber stub, and (ii) a plurality of ferrule gripper arrangements, each associated with one of said ferrule-receiving bores; (b) providing a fiber-stub inversion assembly including: (i) a storage plate, (ii) a plurality of fiber-stub-receiving openings disposed on a surface of said storage plate in a pattern similar to a pattern of said ferrule-receiving bores, and (iii) a support mechanism configured to support said storage plate, said support mechanism including an inversion mechanism for selectively allowing inversion of said storage plate; (c) deploying and clamping a plurality of optical fiber stubs within said ferrule-receiving bores with a first end of each of said fiber stubs projecting from said lower surface; (d) polishing said first ends of said fiber stubs; (e) bringing said plate assembly into juxtaposition with said storage plate such that said ferrule-receiving bores are aligned with said fiber-stub-receiving openings; (f) releasing and off-loading said fiber stubs from said ferrule-receiving bores into said fiber-stub-receiving openings; (g) inverting said plate assembly and bringing said plate assembly into inverted juxtaposition with said storage plate such that said ferrule-receiving bores are aligned with said fiber-stub-receiving openings; (h) reloading the fiber stubs from said fiber-stub-receiving openings into said ferrule-receiving bores and clamping the fiber stubs within said ferrule-receiving bores with a second end of each of said fiber stubs projecting from said lower surface; and (i) polishing the second ends of the fiber stubs.
 20. The method of claim 19, wherein said reloading-includes inverting said plate assembly together with said storage plate.
 21. The method of claim 19, wherein said deploying and said re-loading both include bringing said plate assembly into juxtaposition with a loading calibration surface, said loading calibration surface having a plurality of alignment openings each configured to define a degree of projection of the fiber stub from a corresponding one of said ferrule-receiving bores.
 22. The method of claim 21, wherein said loading calibration surface is implemented as a surface of said storage plate.
 23. The method of claim 19, wherein said deploying and clamping and said re-loading and clamping include operating a locking mechanism to simultaneously operate a plurality of said ferrule gripper arrangements.
 24. The method of claim 19, wherein at least said deploying includes employing an insertion tool including at least one at least one spring-loaded pin for pressing a fiber stub to a fully inserted position within one of said ferrule-receiving bores. 